Compass alarm



y- 1938- J. H. HAMMOND, JR 2,118,082

COMPASS ALARM Filed Feb. 17, 1956 2 Sheets-Sheet l INVENTOR Y John Hays Hammond, Jr.

ATTORN EY May 24, 1938. J. H. HAMMOND, JR

COMPAS S ALARM 2 Sheets-Sheet 2 Filed Feb. 17, 1836 My \SNR.

INVENTOR John Hays Hammond, Jr.-

ATTORNEY Patented May 24, 1938 UNITED STATES PATENT OFFICE 1 Claim.

This invention relates to navigational instruments and more particularly to an improved system for automatically giving a warning when the vessel deviates from a given course.

More specifically the invention provides a system in which an alarm is automatically sounded when the vessel deviates more than a predetermined number of degrees from a set course fora definite interval of time.

10 An object of the invention is to provide a practical, dependable, and efficient system of the type above indicated.

Various other objects and advantages will be r apparent as the nature of the invention is more fully disclosed.

Although the novel features which are believed to be characteristic of this invention will be particularly pointed out in the claims appended hereto, the invention itself, as to its objects and 20 advantages, the mode of its operation and the manner of its organization may be better understood by referring to the following description taken in connection with the accompanying drawings forming a part thereof, in which I 25 Fig. 1 is a top plan view of the instrument with the casing removed and with the associated electrical circuits indicated diagrammatically, and

Fig. 2 is a sectional elevation of the instrument taken on line 2-2 of Fig. 1.

30 In the following description and in the claim parts will be identified by specific names for convenience, but they are intended to be as generic in their application to similar parts as the art will permit.

35 Referring more particularly to the accompanying drawings, a binnacle casing I is mounted on the bridge or other suitable'location on the vessel. A gimbal ring II is mounted in the cas ing ill on pivots I2 and ring i3 is'pivotally mount- 40 ed in the gimbal ring II by means of pivots l5.

Secured to the ring I3 is a second ring [6 on which is mounted a circular frame ll. Mounted in the frame I1 is a compass .bowl liiwhich is made of transparent material such for example as glass.

Over the top of the bowl I8 is mounted a circular lass plate is which is held in position by means of ring 2|. Mounted in the bowl i8 is a pivot 22,

on the point of which is rotatably mounted a 50 compass card 23 which may be of well known and standard construction. Attached to the compass card 23 directly below the north point thereof is a rectangular mirror 25, the width of which only extends a few degrees on either side of the north point of the compass. At the opposite side of the compass card 23 is located a counterweight 25 for balancing the weight of the mirror 25.

Rotatably mounted between the ring I6 and the frame I I is a second bowl 30. The upper edge of this bowl is inclined as shown at 3| and 5 is engraved with the points of the compass as shown in Fig. '1. A segmental hole 32 is cut through the frame I! so as to expose to view the points of the compass engraved on the surface 3i. A lubber line 33 is engraved on the frame I1 on the longitudinal line of the vessel.

Secured to the outside of the bowl 30 is a commutator 35 made of insulating material in which are mounted three slip rings 36, 31, and 38. Ber low the commutator 35 and secured to the bowl 30 is a beveled gear 39 with which meshes a beveled pinion 40. This pinion is secured to one end of a shaft 4|, which is rotatably mounted in a bracket 42 forming part of the ring l3. A knurled knob 43 is secured to the other end of the shaft 4|. A spiral compression spring 45 surrounds the shaft 4l between the pinion 40 and the bracket 42, thus locking the pinion 40 against the gear 39 to keep the latter from turning due to vibration, etc. A hinged door 46 is provided in the casing III in order to permit access to the knurled knob 43.

The slip rings 36 and 31 are connected to a lamp 41 which is mounted in the bowl 311. The light from this lamp is focused by means of a lens system 48 into a beam 49. This beam of light is reflected from a mirror 50 onto the mirror 25, mounted on the compass card 23. From the mirror 25 the beam of light is reflected by two mirrors 5i and 52 onto a photo-electric cell 53. This cell may be of the type known as a photronic cell manufactured by the Weston Electrical Instrument Company which does not need a source of power for its operation. The photo-electric cell 53 is connected to the two slip rings 31 and 38. 49

The three slip rings 36, 31', and 33 are engaged by three brushes 55, 56, and 51 which are mounted on a block of insulating material 58 which is secured to the ring i3. The three brushes 55,

56, and 51 are connected to a three conductor cable 62 having conductors 59, 60, and GI (Fig.

1-) This cable passes from the block of insulating material 53 along the under surface of the gimbal ring II and passes out through the casing Ill. The conductor 59 is.connected through a switch 63 to one side of a source of alternating current 55, the other side of this source being connected to the conductor 63. The conductor 50 is connected by a branch conductor 65 to one side of the winding of a sensitive relay-ii, the

other side of thewinding of which is connected to the conductor 6|.

The armature of the relay 6! is connected through a switch 88 to one side of the winding of a solenoid 69, the other side of the winding of which is connected through a battery 18 to the back contact of the relay 61. The solenoid 89 is provided with a core H to which is secured a collar I2. Between the collar 12 and the solenoid 89 is a spiral compression spring I3 which tends to hold the core 1| in its outmost position. Secured to the upper end of the core H is a piston I5 which reciprocates in a cylinder 16. This cylinder is provided with a large port l1 and a small port 18. A valve 19 is mounted over the large port I1.

Secured to the core H is an arm 8| of insulating material to which is attached a block 82 of con-' ducting material. Located in the path of travel of the block 82 are two contacts 85 and 86, the

former being connected to one'side of a battery 81 and the latter through a switch 88 to a lamp 89 and through a switch 98 to a bell 9|. The return circuits from the lamp 89 and the bell 9| are connected to the other side of the battery 81.

In the operation of the form of the invention.

just described, after it is determined upon which course the. vessel is to proceed, the door 48 in the binnacle' casing I8 is opened and the knurled knob.

88 is turned so as to cause rotation of the bowl 88 by means of the pinion 48 and the gear 89 ,until the desired course as shown by the compass scale engraved on the surface 3| registers with the lubber line 93. In the case shown in the accompanying figures, the desired course is due north so that this point registers with the lubber line 83. The helmsman then steers the vessel so that it is heading due north as indicated by the compass card 23. At this time the mirror 25 on the under surface of the compass card 23 will be in line with the optical system carried in-the bowl 38 so that light from the lamp 1 will impinge upon the photo-electric cell 58, thus energizing this cell which in turn will cause the energization of the sensitive relay 81. i

The switch 68 is then'closed and either or both of the switches 88 and 98'are closed as desired. As

. long-as the vessel remains on the predetermined course, in this case due north, the sensitive relay 8'! will remain energized thus preventing the em ergization of the solenoid 69. If, however, the vessel deviates more than a predetermined number of degrees from this course, the mirror 25 will move out of line with theoptical system, thereby shutting off the light to' the photo-electric cell 53 which in turn will cause deenergization of the sensitive relay 61. This in turn will close the circuit through the solenoid 89, thus causing the core of this solenoid to be moved slowly downward at a rate which is determined by the amount of-air entering the port 18.

If the vessel remains 01f its course for a prede, termined interval of time, the conducting block '82 will engage the contacts and 86, thereby tinue until the vessel is returned to its proper course, at which time the mirror 25 will again be in line with the optical system so that the photo-electric cell 53.will be again illuminated. This will energize the relay 81, thereby deenerglzing the solenoid 69. When this occurs, the core II will be moved rapidly upwards under the action of the spring 13 and due to the air freely passing out of the large port 11. The variation in azimuth required to interrupt the light beam is determined by the characteristics of the mirror 25 which may be designed to cause actuation of the warning signal after any desired angular deviation.

If the vessel deviates from its predetermined course sufficiently to energize the relay but is returned to the course before the core-1| of the solenoid-89 has moved sufilciently to cause the engagement of the contacts 85 and 88 by the conducting block 82,, the relay 8'! will be 'deenergized thereby allowing the core 'I| tomove rapidly upward to its initial position without causing the alarm to be sounded.

that it is not limited thereto, but any suitable number or type of systems may be employed which may be located at any part of the ship such as-in the captain's cabin or elsewhere to apprise the captain or other officers of the vessel that the proper course is not being maintained.

It is to be understood that any desired control mechanisms such as asteering control may be substituted for the alarm or may beconnected to the battery 81 in addition to the alarm signals set forth.- The circuits disclosed are merely illustrative of various control devices that can be actuated in response to a predetermined variation in azimuth of the vessel.

Although only a specific embodiment of the invention has been shown herein, it is to be understood that the invention is not limited to any specific construction but may be embodied in various forms without departing from the spirit of the invention or the scope of the appended claim.

What is claimed is:

In a navigational system, a housing, a compass card movable with respect thereto to indicate direction, a photoelectric system carried by said signal circuit when energized for a given time" interval, an energizing circuit for said electromagnetic means, a-relay biased to normally close said energizing circuit, and means controlled by said photoelectric cell to hold said relay open when said .light is focused thereon by said compass card, whereby said signal circuit is energized only in response to a deviation of said housing rela-.

tively to said card in either direction by more than a given angle and for said given time interval. JOHN HAYS HAMMOND, JR. 

